Together, both Nipah and Hendra viruses are members of the genus Henipavirus, a new class of virus in the Paramyxoviridae family. The mortality and morbidity associated with outbreaks of these viruses are significant and frequently severe.
In 1994, the first Australian outbreak of a highly-pathogenic virus occurred in the Brisbane suburb of Hendra. Hendra virus (HeV) (family Paramyxoviridae, genus Henipavirus) was identified as a novel causative agent (Mitchell et al., 2008). HeV is carried asymptomatically by flying foxes, and infects humans via contact with infected horses which act as an intermediary host. Since 2004, 31 outbreaks of HeV have occurred in Australia (Marsh et al., 2010), with 17 outbreaks occurring from June to August 2011. The virus is highly-pathogenic in humans (7 reported cases, 4 fatalities, mortality rate 57%), but little is known about disease pathogenesis. There are currently no licensed vaccines or therapeutics to treat HeV infections.
Nipah virus (NiV) is an emerging zoonotic virus (a virus transmitted to humans from animals) that is closely related to Hendra virus. In infected people, Nipah virus causes severe illness characterized by inflammation of the brain (encephalitis) or respiratory diseases. It can also cause severe disease in animals such as pigs, resulting in significant economic losses for farmers.
Nipah virus was first recognized in 1999 during an outbreak among pig farmers in Malaysia. Since then, there have been another 12 outbreaks, all in South Asia. Although Nipah virus has caused only a few outbreaks, it infects a wide range of animals and causes severe disease and death in people, making it a serious public health concern. There are currently no drugs or vaccines available to treat Nipah virus infection. Intensive supportive care with treatment of symptoms is the main approach to managing the infection in people.
In addition to Henipaviruses, there are a number of viruses that are capable of causing significant disease outbreaks. Outbreaks can spread very rapidly in emergency situations and lead to high morbidity and mortality rates. Thus, it is desirable to detect an outbreak as early as possible so as to control the spread of disease among the population at risk.
Thus, there remains a need for methods for diagnosing or detecting virus infection and for methods for the treatment or prevention of virus infection. In addition, there is a need for methods for the early detection of infection by viruses that cause outbreaks leading to significant morbidity and mortality.